Yeah...I noticed some time back. I guess the thing I am having trouble wrapping my head around is, how do you know how much to use? With the standard culture a 1/4 tsp is 1/4 tsp and will always be 1/4 tsp (for the same make), but with the mother culture it seems to be a bit less definable, in a sense...on the other hand, I like the idea of working with a "live" culture that starts working almost immediately. I noticed your "innoculation" period was 15 minutes.

Thanks! I will check out Sailor's post...had read it sometime back, but didnt think it really applied to my make schedule/type/size...What I may do is make a much smaller amount of the mother culture to use to begin with. If I remember correctly he was making like quart amounts of each culture.

Mother cultures are fairly easy. I just buy a box of UHT milk, which is no good for hard cheeses (apparently semi-lactics are ok) but it is sterile. Add a few grains of meso culture and let it sit around 20 C for 12 to 24 hours. If you use thermo culture, put it in a warmer location, around 28 C or so. I just either leave it on the kitchen counter (meso) or in the hot water cupboard (thermo). Anyway, it will thicken, like gluggy yogurt. Pour this into steralised ice cube trays and freeze. Bag the cubes, label, and use 4-6 for a 10 Litre make.

- Jeff

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Thanks for the suggestion! U-P milk would be perfect....am working on a batch right now, using the culture mix I use for cheddars, since I am currently focusing on them and will use the mother culture in my next make, tomorrow

Even though UP/UHT milk is technically sterile there can be post-pasteurization contamination, especially during bottling. If you leave an unopened bottle of UP/UHT on your counter at room temperature it will last longer than regular milk, but it will still go bad. That's from the contaminants.

Yes, it's "sterile" before you open it, but once opened it is subject to contamination which leads to spoilage. But, by adding the culture (and loosely closing the lid, so gas can escape) the culture should out compete any pathogen. Some people have suggested that one could then use their last ice cube to start a new batch, etc, but I'm not sure that's such a good idea. The blend ratio of cultures would get out of whack after a while if you're using a mix (like FD) and, you risk perpetuating any pathogen that did get in. Might be in too small a number for a batch or two, but given the opportunity to compete, it may end up being the winner after a few generations.

- Jeff

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The wise do not always start out on the right path, but they do know when to change course.

Some people have suggested that one could then use their last ice cube to start a new batch, etc, but I'm not sure that's such a good idea. The blend ratio of cultures would get out of whack after a while if you're using a mix (like FD) and, you risk perpetuating any pathogen that did get in. Might be in too small a number for a batch or two, but given the opportunity to compete, it may end up being the winner after a few generations.

That would be similar to a movie made back in the 1990's, Multiplicity, where a guy who is overworked and overstressed, finds a way to duplicate himself. That works for a while and he's able to spread himself out and be more effective. That works okay until one day his clone wants a buddy so he clones himself. A clone making a clone. Hey, now there's three versions of this one guy. The two clones are very different from the original guy, but still viable. Then the cloned clone makes a buddy for himself. This cloned clone of a clone is not so high quality. In a word, he's stupid.

Such might be the case where you try to propagate cultures from grown cultures. Better to use fresh.

Yes, it's "sterile" before you open it, but once opened it is subject to contamination which leads to spoilage.

There is almost no such thing as "sterile", especially in a home environment. Some bacteria and yeast can form spores which can survive even boiling water. Anyone who cans at home has probably seen this problem. Hospitals and labs use "autoclaves" that combine high heat and pressure to truly sterilize tools and equipment.

As I said above, leave an UNOPENED container of UP/UHT at room temp and it will spoil from the organisms that either survived pasteurization or were reintroduced during packaging. The concern here is not pathogens, except maybe Clostridium (Botulism). Those are generally killed off during normal pasteurization. So UP is really overkill for pathogens, but goes a step farther towards sterilization and does kill off MOST spoilage organisms, but not all.

Here a gallon of skim milk is just $2.50/gallon or about 63¢ for a quart of Mother Culture. Around here UP generally means "organic", which is 4 times the price.

When preserving a whey culture, you also preserve a reserve culture in the form of yogurt. A portion of this can be frozen and kept for a very long period of time (a few years)

This is important because we work with unpasteurized milk, meaning there are a lot of organisms present to possibly compete with our culture bacteria. If we would just hold over the whey by itself, reason would tell us it would eventually become a different mix of bacteria. But we have 2 ways of getting around that. First, we add a tablespoon or so of our yogurt into every liter of preserved whey. This reintroduces the good bacteria. Second, the whey is heated to a fairly high temperature, which is going to kill off most unwanted organisms but allow the thermos to live on (our cheeses are thermophilic). So our whey culture is reinforced, quickly heated, then quickly cooled and incubated overnight. This keeps our culture going strong.

Also important is that when we make our yogurt, we sterilize the milk as part of the process even if using storebought stuff. This for two reasons, to kill off anything that might compete with our culture, and to break down certain proteins allowing the yogurt to set up thicker (this is nice if you want to eat it)

Also, all culture-handling equipment is repeatedly cleaned and sanitized.

You could use frozen culture to start a new batch, but you would have to go through a multi-step process.

Thaw the culture, slowly warm it up to incubating temp, and leave it alone for a few hours.

You should test you cultures when incubating like this, and they will fall into a fairly narrow acceptable range of acidity (%TA) the specifics will vary with the culture used, and I would give degrees SH which would probably mean nothing to you anyway :/

Sterilize some milk yourself, and flash cool it down to incubating temp with a cold water bathadd the thawed culture stock. This is a very small quantity. incubate this stuff overnight. sterilize some more milk, this time a liter or so. if using a thermo culture, quickly heat the cultured milk to say 150 degrees with a hot water bath, then with a cold water bath back down to incubating temp. Add cultured milk to sterilized milk. incubate this overnight.

this should give you a nice, happy thermophilic culture. It will no longer be exactly what you got in the package but that is not necessarily a bad thing. This will yield you a culture more akin to a traditional Old World culture, rather than a laboratory culture. It will have dozens of bacteria growing in it, instead of two or three, but be assured they are good.

Ah, here the UHT milk is not organic, I think it's just so you can keep the milk in the cupboard rather than in the fridge (as it will keep that way for weeks, maybe months, until opened). I put sterile in quotes to indicate that I was using the term a bit loosely and didn't mean to imply it would last forever, etc, I just meant the UHT milk is exceptionally low in stuff that would compete with the added cheese culture, so a mother culture made from it will be just what you add, but I accept your point that the home is not exactly a food lab and that, if left out on the counter even unopened it will eventually go off, but that's at a time frame well beyond what we're dealing with here. Also, there's always the risk of contamination when you open something in the home. I'm making the assumption that anyone who is making cheese at home is aware of the need to minimize contamination, and would recognize that a bit of extra care should be taken with mother cultures since they will be used to make a number of cheeses.

Anyway, here UHT milk is not exceptionally expensive, and I've found it to be a good choice for making mother cultures for the above reasons. That's all.

- Jeff

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Hospitals and labs use "autoclaves" that combine high heat and pressure to truly sterilize tools and equipment

Not sure what would happen to the milk, but you can use a pressure cooker to sterilize your milk. temp will depend on how much you can pressurize your cooker.

When making a culture I often just put some storebought milk in a glass jar (dilute with some water if its not skim milk), put it in the microwave and nuke it untill it starts to boil over, cool it down and pitch some culture.

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Amatuar winemaker,baker, cook and musician not in any particular order.

Thanks curd nerd. There are a few Dick Smiths still around, though they are closing out. Will have a look, although many things in NZ gain a lot of monetary weight from crossing the Tasman ; must be from the humidity?

- Jeff

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The wise do not always start out on the right path, but they do know when to change course.